An Interagency collaboration for developing decision tools: How the U.S. Geological Survey works wit

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An Inter-agency collaboration for developing
decision tools How the U.S. Geological Survey
works with the National Weather Service to issue
warnings for post-fire flash floods and debris
flows

• Sue Cannon, USGS

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• Wildfire

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Wildfire potentially disastrous consequences
Its not over once the smoke clears..
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Wildfire effects on watersheds

• Consumption of rainfall-intercepting canopy and
  of soil-mantling litter and duff
• Intensive drying of the soil
• Generation of wood ash and water-repellent soils
• Removal of obstructions to flow

Results in dramatic changes in erodibility,
infiltration, and runoff
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Debris flows!!

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Southern California Wildfires Oct 21, 2003
gt700,000 acres
Simi, Piru, Verdale
Grand Prix, Old
Paradise, Cedar
NASA Image
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Debris flows
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Debris Flow Hazards to Life and Property
Camp St Sophia, Dec 25, 2003
Cable Canyon, Dec 25, 2003
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Report of the Joint NOAA-USGS Debris Flow
Warning System Task Force
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Task Force Assignment

• Establish a prototype flash flood and debris flow
  warning system for burned areas in Southern
  California

• Identify
• scientific opportunities,
• necessary advancements, and
• costs

San Bernardino Mountains, Dec. 2003

• Expand system to
• other burned areas,
• unburned areas, and
• to a national scope

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Prototype Warning System

• Save lives and protect property
• Provide timely information to emergency response
  personnel and the public
• Demonstrate merging of NOAA and USGS
  state-of-the-art forecast and prediction tools

Wind profiling radar
Missionary Ridge Fire, Durango CO
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Prototype Warning System
Links NWS and USGS expertise and NWS 24x7
operational capabilities
Southern California radar coverage (blue
regions), and real-time rain gage locations (red
dots).
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Rainfall thresholds
Santa Lucia Range, Sierra Madre, and Santa Ynez,
Topatopa, Santa Susana and Santa Monica Mtns
San Gabriel, San Bernardino and San Jacinto Mtns
Peninsular Ranges
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Rainfall thresholds
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Flash Flood Monitoring and Prediction (FFMP)

• Continuous monitoring of rainfall rates and
  accumulations in comparison to threshold
  conditions for individual stream basins
• Automatically alerts forecasters when a
  dangerous flash flood or debris flow situation
  may be developing

Map of Storm Precipitation
Basin conditions relative to rainfall thresholds
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Prototype System Operation
Wildfire in southern CA steeplands
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Outlooks Natural Hazards Support System web
site
Southern CA Fire Perimeters August 25, 2005
The watersheds burned this summer by the Tovey
Fire in Los Angeles County near the town of
Palmdale are particularly susceptible to flash
floods and debris flows during rainstorms..
http//nhss.cr.usgs.gov/
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Watches

• Risk of hazardous weather or hydrologic event
  has increased significantly, but its occurrence,
  location, and/or timing are still uncertain
• 3 days to a few hours lead time

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Warnings

• Issued when hazardous weather or hydrologic event
  is occurring, is imminent, or has a very high
  probability of occurring

- 1 day to 30 minute lead times
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A test of the System October 19, 2005
Harvard Fire
Burbank
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Immediate System Expansion

• Refine existing rainfall thresholds and develop
  new ones

Santa Lucia Range, Sierra Madre, and Santa Ynez,
Topatopa, Santa Susana and Santa Monica Mtns
San Gabriel, San Bernardino and San Jacinto Mtns
Peninsular Ranges
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Potential System Expansion

• Provide spatially specific information as storms
  develop

Burned area
0.6 inches of rainfall in 30 minutes
0-25 26-50 51-75 76-100
Probability of debris flow from drainages burned
by the Missionary Ridge Fire near Durango,
Colorado
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Example
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Model Implementation
1. Delineate basins of interest
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Model Implementation
2. Extract data necessary for model input for
each basin
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3. Calculate Probability for each basin, and
parse into classes
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Probability of debris-flow occurrence
Missionary Ridge Fire, Colorado
Probability of Debris- Flow Occurrence
1-25 25-50 50-75
75-100
Burn Perimeter
In response to 0.5 inches of rainfall 30 minutes
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Potential System Expansion
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Intensive Research Area Harvard Fire
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Potential Future Development

• Expansion to unburned areas throughout the US

Seattle, WA
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Questions???